Terminal Problem?
 

OK - so I am driving along minding my own business - low speed (sub 20 mph), and with no notice the "ASC not Available" warning comes up. No concern, but then "TRAC not Available" arrives - still not particularly worrying, but then it says "Failsafe Engine Mode", and to round off my day "Gearbox Fault". I gently tiptoed the 400 yards into the company car park (phew, I'm glad it was close) with no clunks or smoke or any drama, but then as I put it into reverse to park I got a clunk. It did go into reverse, and then safely into Neutral.

So - I don't have a code reader or anything, but just to give me a warning of what may be in my future would anyone like to guess what happened?

(I think a trip on the back of the AA truck is in my immediate future, but I meant after that!)

2000 (W reg) 4.0 XK8 coupe. 98,000 miles.

When multiple electrical/electronic faults suddenly appear, first check your battery.

Graham

Thanks, I will.

+1

Classic signs of a battery which can start the car but not run it properly.

May be failing or simply rather flat (may recharge / may not).

Battery reads 12.2 with the engine off, 14.1 with the engine on.

Incidentally when I turned the engine back on (to run the above check), all of the alarms had disappeared. Emboldened I drove around the car park. Sounds sweet as ever.

I called the AA, and they couldn't find any codes stored (? Is their equipment compatible with these cars?), so I drove it around a bit and the warnings didn't come back.

So ... watch this space, I guess.

Anyone have any advice regarding what I could do/ check to ensure the issue doesn't return?

To me, it sounds like a problem with the ABS system, likely the rear sensors (or harnesses). If the car does not have input from the ABS, it cannot operate the ABS, TRAC becomes also unable to function, and the gearbox becomes unable to read road speed that way either, hence "Gearbox Fault". Best of course would be to capture those codes as they happen to get some confirmation, but these are Jaguar specific, a generic OBDII reader will not do.

Barring that, it would not hurt to do some careful inspection. Remove each wheel, remove/clean/inspect the sensors. Double check the harnesses and rubber boots. Measure resistance for anything odd. Double check the reluctor ring on the axles (they need to be completely solid).

Also double check all the wheel bearings. (Very) loose bearings can put the reluctor ring out of range for the sensor and throw codes.

If all of these sanity checks fail, the ABS unit itself might need a rebuild, especially if there are no code stored (the common failure is about module power).

Best of luck, keep us posted.

A battery at 12.2V is too low. I would replace it and see what happens.

^^ Agreed. 12.2 volts will cause problems....

I get that 12.2 is low, but the car was running at the time, so the alternator was keeping it at 14+.

But my position is not to question life, I definitely foresee a CTEK in my future.

... and as soon as my Indy gets back from his holidays I will let him (and his Jag specific code reader) loose on the sensors.

It wouldn't hurt to check your battery terminals and ground strap. But +1 on the battery too.

12.2 is so low that the battery is likely failing and can no longer smooth the alternator output properly - and so you can expect spikes that confuse modules.

If it's not the battery your next step is to get the codes from all the modules. You'll need a decent tool to do that or pay someone quite a bit.

Thanks all.

I had a similar experience a couple of weeks ago while vacationing in New Brunswick, Canada 700ish miles from home. It too cleared up on the next restart. It's been fine since.